Commit a907f3a6 authored by Jaegeuk Kim's avatar Jaegeuk Kim
Browse files

f2fs: add a sysfs entry to reclaim POSIX_FADV_NOREUSE pages 



1. fadvise(fd1, POSIX_FADV_NOREUSE, {0,3});
2. fadvise(fd2, POSIX_FADV_NOREUSE, {1,2});
3. fadvise(fd3, POSIX_FADV_NOREUSE, {3,1});
4. echo 1024 > /sys/fs/f2fs/tuning/reclaim_caches_kb

This gives a way to reclaim file-backed pages by iterating all f2fs mounts until
reclaiming 1MB page cache ranges, registered by #1, #2, and #3.

5. cat /sys/fs/f2fs/tuning/reclaim_caches_kb
-> gives total number of registered file ranges.

Reviewed-by: default avatarChao Yu <chao@kernel.org>
Signed-off-by: default avatarJaegeuk Kim <jaegeuk@kernel.org>
parent ef0c333c

Documentation/ABI/testing/sysfs-fs-f2fs

+7 −0
Original line number Diff line number Diff line
@@ -828,3 +828,10 @@ Date: November 2024 
Contact:	"Chao Yu" <chao@kernel.org>

Description:	It controls max read extent count for per-inode, the value of threshold

		is 10240 by default.



What:		/sys/fs/f2fs/tuning/reclaim_caches_kb

Date:		February 2025

Contact:	"Jaegeuk Kim" <jaegeuk@kernel.org>

Description:	It reclaims the given KBs of file-backed pages registered by

		ioctl(F2FS_IOC_DONATE_RANGE).

		For example, writing N tries to drop N KBs spaces in LRU.

fs/f2fs/f2fs.h

+2 −0
Original line number Diff line number Diff line
@@ -4243,6 +4243,8 @@ unsigned long f2fs_shrink_count(struct shrinker *shrink, 
			struct shrink_control *sc);

unsigned long f2fs_shrink_scan(struct shrinker *shrink,

			struct shrink_control *sc);

unsigned int f2fs_donate_files(void);

void f2fs_reclaim_caches(unsigned int reclaim_caches_kb);

void f2fs_join_shrinker(struct f2fs_sb_info *sbi);

void f2fs_leave_shrinker(struct f2fs_sb_info *sbi);

fs/f2fs/shrinker.c

+90 −0
Original line number Diff line number Diff line
@@ -130,6 +130,96 @@ unsigned long f2fs_shrink_scan(struct shrinker *shrink, 
	return freed;

}



unsigned int f2fs_donate_files(void)

{

	struct f2fs_sb_info *sbi;

	struct list_head *p;

	unsigned int donate_files = 0;



	spin_lock(&f2fs_list_lock);

	p = f2fs_list.next;

	while (p != &f2fs_list) {

		sbi = list_entry(p, struct f2fs_sb_info, s_list);



		/* stop f2fs_put_super */

		if (!mutex_trylock(&sbi->umount_mutex)) {

			p = p->next;

			continue;

		}

		spin_unlock(&f2fs_list_lock);



		donate_files += sbi->donate_files;



		spin_lock(&f2fs_list_lock);

		p = p->next;

		mutex_unlock(&sbi->umount_mutex);

	}

	spin_unlock(&f2fs_list_lock);



	return donate_files;

}



static unsigned int do_reclaim_caches(struct f2fs_sb_info *sbi,

				unsigned int reclaim_caches_kb)

{

	struct inode *inode;

	struct f2fs_inode_info *fi;

	unsigned int nfiles = sbi->donate_files;

	pgoff_t npages = reclaim_caches_kb >> (PAGE_SHIFT - 10);



	while (npages && nfiles--) {

		pgoff_t len;



		spin_lock(&sbi->inode_lock[DONATE_INODE]);

		if (list_empty(&sbi->inode_list[DONATE_INODE])) {

			spin_unlock(&sbi->inode_lock[DONATE_INODE]);

			break;

		}

		fi = list_first_entry(&sbi->inode_list[DONATE_INODE],

					struct f2fs_inode_info, gdonate_list);

		list_move_tail(&fi->gdonate_list, &sbi->inode_list[DONATE_INODE]);

		inode = igrab(&fi->vfs_inode);

		spin_unlock(&sbi->inode_lock[DONATE_INODE]);



		if (!inode)

			continue;



		len = fi->donate_end - fi->donate_start + 1;

		npages = npages < len ? 0 : npages - len;

		invalidate_inode_pages2_range(inode->i_mapping,

					fi->donate_start, fi->donate_end);

		iput(inode);

		cond_resched();

	}

	return npages << (PAGE_SHIFT - 10);

}



void f2fs_reclaim_caches(unsigned int reclaim_caches_kb)

{

	struct f2fs_sb_info *sbi;

	struct list_head *p;



	spin_lock(&f2fs_list_lock);

	p = f2fs_list.next;

	while (p != &f2fs_list && reclaim_caches_kb) {

		sbi = list_entry(p, struct f2fs_sb_info, s_list);



		/* stop f2fs_put_super */

		if (!mutex_trylock(&sbi->umount_mutex)) {

			p = p->next;

			continue;

		}

		spin_unlock(&f2fs_list_lock);



		reclaim_caches_kb = do_reclaim_caches(sbi, reclaim_caches_kb);



		spin_lock(&f2fs_list_lock);

		p = p->next;

		mutex_unlock(&sbi->umount_mutex);

	}

	spin_unlock(&f2fs_list_lock);

}



void f2fs_join_shrinker(struct f2fs_sb_info *sbi)

{

	spin_lock(&f2fs_list_lock);

fs/f2fs/sysfs.c

+63 −0
Original line number Diff line number Diff line
@@ -916,6 +916,39 @@ static struct f2fs_base_attr f2fs_base_attr_##_name = { \ 
	.show	= f2fs_feature_show,				\

}



static ssize_t f2fs_tune_show(struct f2fs_base_attr *a, char *buf)

{

	unsigned int res = 0;



	if (!strcmp(a->attr.name, "reclaim_caches_kb"))

		res = f2fs_donate_files();



	return sysfs_emit(buf, "%u\n", res);

}



static ssize_t f2fs_tune_store(struct f2fs_base_attr *a,

			const char *buf, size_t count)

{

	unsigned long t;

	int ret;



	ret = kstrtoul(skip_spaces(buf), 0, &t);

	if (ret)

		return ret;



	if (!strcmp(a->attr.name, "reclaim_caches_kb"))

		f2fs_reclaim_caches(t);



	return count;

}



#define F2FS_TUNE_RW_ATTR(_name)				\

static struct f2fs_base_attr f2fs_base_attr_##_name = {		\

	.attr = {.name = __stringify(_name), .mode = 0644 },	\

	.show	= f2fs_tune_show,				\

	.store	= f2fs_tune_store,				\

}



static ssize_t f2fs_sb_feature_show(struct f2fs_attr *a,

		struct f2fs_sb_info *sbi, char *buf)

{
@@ -1368,6 +1401,14 @@ static struct attribute *f2fs_sb_feat_attrs[] = { 
};

ATTRIBUTE_GROUPS(f2fs_sb_feat);



F2FS_TUNE_RW_ATTR(reclaim_caches_kb);



static struct attribute *f2fs_tune_attrs[] = {

	BASE_ATTR_LIST(reclaim_caches_kb),

	NULL,

};

ATTRIBUTE_GROUPS(f2fs_tune);



static const struct sysfs_ops f2fs_attr_ops = {

	.show	= f2fs_attr_show,

	.store	= f2fs_attr_store,
@@ -1401,6 +1442,20 @@ static struct kobject f2fs_feat = { 
	.kset	= &f2fs_kset,

};



static const struct sysfs_ops f2fs_tune_attr_ops = {

	.show	= f2fs_base_attr_show,

	.store	= f2fs_base_attr_store,

};



static const struct kobj_type f2fs_tune_ktype = {

	.default_groups = f2fs_tune_groups,

	.sysfs_ops	= &f2fs_tune_attr_ops,

};



static struct kobject f2fs_tune = {

	.kset	= &f2fs_kset,

};



static ssize_t f2fs_stat_attr_show(struct kobject *kobj,

				struct attribute *attr, char *buf)

{
@@ -1637,6 +1692,11 @@ int __init f2fs_init_sysfs(void) 
	if (ret)

		goto put_kobject;



	ret = kobject_init_and_add(&f2fs_tune, &f2fs_tune_ktype,

				   NULL, "tuning");

	if (ret)

		goto put_kobject;



	f2fs_proc_root = proc_mkdir("fs/f2fs", NULL);

	if (!f2fs_proc_root) {

		ret = -ENOMEM;
@@ -1644,7 +1704,9 @@ int __init f2fs_init_sysfs(void) 
	}



	return 0;



put_kobject:

	kobject_put(&f2fs_tune);

	kobject_put(&f2fs_feat);

	kset_unregister(&f2fs_kset);

	return ret;
@@ -1652,6 +1714,7 @@ int __init f2fs_init_sysfs(void) 


void f2fs_exit_sysfs(void)

{

	kobject_put(&f2fs_tune);

	kobject_put(&f2fs_feat);

	kset_unregister(&f2fs_kset);

	remove_proc_entry("fs/f2fs", NULL);